Lee, Charles Kai-WuLaughlin, Daniel C.Bottos, Eric M.Caruso, TancrediJoy, KurtBarrett, John E.Brabyn, LarsNielsen, Uffe N.Adams, Byron J.Wall, Diana H.Hopkins, David W.Pointing, Stephen B.McDonald, Ian R.Cowan, Don A.Banks, Jonathan C.Stichbury, GlenJones, IrfonZawar-Reza, PeymanKaturji, MarwanHogg, Ian D.Sparrow, Ashley D.Storey, Bryan C.Green, T.G. AllanCary, S. Craig2019-05-2620192019-05-262019Lee, C. K., Laughlin, D. C., Bottos, E. M., Caruso, T., Joy, K., Barrett, J. E., … Cary, S. C. (2019). Biotic interactions are an unexpected yet critical control on the complexity of an abiotically driven polar ecosystem. Communications Biology, 2, 62. https://doi.org/10.1038/s42003-018-0274-5https://hdl.handle.net/10289/12558Abiotic and biotic factors control ecosystem biodiversity, but their relative contributions remain unclear. The ultraoligotrophic ecosystem of the Antarctic Dry Valleys, a simple yet highly heterogeneous ecosystem, is a natural laboratory well-suited for resolving the abiotic and biotic controls of community structure. We undertook a multidisciplinary investigation to capture ecologically relevant biotic and abiotic attributes of more than 500 sites in the Dry Valleys, encompassing observed landscape heterogeneities across more than 200 km². Using richness of autotrophic and heterotrophic taxa as a proxy for functional complexity, we linked measured variables in a parsimonious yet comprehensive structural equation model that explained significant variations in biological complexity and identified landscape-scale and fine-scale abiotic factors as the primary drivers of diversity. However, the inclusion of linkages among functional groups was essential for constructing the best-fitting model. Our findings support the notion that biotic interactions make crucial contributions even in an extremely simple ecosystem.application/pdfenThis article is licensed under a Creative Commons Attribution 4.0 International License. © The Author(s) 2019Journal Article10.1038/s42003-018-0274-52399-3642